Ophthalmic lenses may be made by any of a wide variety of processes. In one such process, one or more resin layers is cast onto an optical preform to form the desired lens. In certain methods for casting a layer onto a preform, the mold assembly is made of a first mold and the optical preform that serves as the second mold. The preform and first mold are positioned in relation to each other, a polymerizable resin is dispersed between the preform and first mold, and the resin is polymerized to produce a lens from the cast layer and the preform.
A number of mechanical components, such as gaskets, O-rings, and the like have been used to contain the polymerizable resin within the mold assembly. However, the known mechanical components for resin containment are disadvantageous because of the need to clean the components. Additionally, the component size required may vary with variations in the size and shape of the optical preform and mold. Therefore, a need exists for a means to contain the resin that avoids the problems inherent in the use of mechanical components for containing the resin.